<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>属性</title>
</head>
<body>
    <div class="cls">第一个div</div>
    <div class="cls">第二个div</div>
    <div id="d1">第三个div</div>
    <div id="d2">第四个div</div>
    <div style="background-color: #ff0000">第五个div</div>
</body>
</html>